According to the recent trend of lighting technology, an LED has been employed as a light source, in order to reduce energy.
A high-brightness LED is differentiated from other light sources in terms of various aspects such as energy consumption, lifetime, and light quality.
However, a lighting apparatus using the LED as a light source requires a large number of additional circuits, because the LED is driven by a constant current.
In order to solve the above-described problem, an AC direct-type lighting apparatus has been developed.
The AC direct-type LED lighting apparatus generates a rectified voltage from a commercial AC power supply, and drives an LED. Since the AC direct-type LED lighting apparatus directly uses the rectified voltage as an input voltage without using an inductor and capacitor, the AC direct-type LED lighting apparatus has a satisfactory power factor.
In general, an LED lamp of the LED lighting apparatus includes a large number of LEDs which are coupled in series.
The LED lighting apparatus may be used in various power supply environments. The environment for supplying power may differ in each building or house, and differ in each region or country. Furthermore, the LED lighting apparatus may be placed in a temporarily unstable power supply environment in addition to the above-described environment.
In the above-described power supply environment, the LED lighting apparatus may receive a rectified voltage having a lower level than the rectified voltage which is designed to drive the lamp. In this case, the LED lighting apparatus may not emit light at a designed luminance.
Furthermore, when the LED lighting apparatus is operated in an unstable power supply environment, the LED lighting apparatus may not maintain uniform luminance due to a temporary drop of the rectified voltage.
Thus, the conventional LED lighting apparatus may not maintain uniform luminance due to the above-described environmental factors.